Throughout the long history of music there have been numerous systems for selecting the pitch of various notes to comprise a basic scale for purposes of musical composition. The player of any musical instrument is concerned with but two of these systems. These are the scale of equal temperament and the scale of just intonation. The unit for measuring musical intervals is the cent; 1200 cents equalling an octave. In the scale of equal temperament, the octave of 1200 cents is divided into 12 equal parts and the interval between each note in the chromatic scale of equal temperament is 100 cents. From the 12 notes of the chromatic scale of equal temperament, various notes are selected to construct scales. The most basic of these to the music of the west is the diatonic 8 tone scale (7 different notes, the 8th being a repetition of the 1st). From a starting point, or keynote, the diatonic scale proceeds progressively through all the notes of the musical alphabet (A through G). The kind of diatonic scale is determined by its starting note and the resulting arrangement of whole notes and semitones.
While the scale of equal temperament is a man-made scale devised as a solution to the problem of tuning fixed tuned instruments, the scale of just intonation is a result of nature. The notes in the scale of just intonation are derived from the notes of the harmonic series or series of partial tones that comprise a musical note. The just, or pure, musical interval is the most consonant or agreeable arrangement possible of the notes contained in it. In the scale of just intonation the notes are unevenly spaced and are not always of the same pitch. For example, in the just major scale, the first and eighth notes coincide with the corresponding equal tempered note, the second note is +4 cents, the third note is -14 cents, the fourth note is -2 cents, the fifth note is +2 cents, the sixth note is -16 cents, and the seventh note is -12 cents different in pitch than the corresponding note in the scale of equal temperament.
For example, in the key of A major, A is the key note or first note in the scale and its pitch is chosen to coincide with the intonation of A in the scale of equal temperament. In the scale of G major and G natural minor, the note A appears in the second position (after the first note of G) and its pitch would be +4 cents above the pitch of an A in the scale of equal temperament. Similarly, in the key of F major, A is the third note in the eight note diatonic scale and its pitch would be -14 cents different from the note A in the scale of equal temperament. By extending this analysis further, it can be shown that the pitch of the note A should be adjusted to +16 cents (+ or -2 cents); -14 cents (+ or -2 cents); or 0 cents (+4 cents -2 cents) in order to achieve a full range of just intonation scales of varying keys wherein the note A appears at different steps within the diatonic scales. This is illustrated by Table 1.
TABLE 1 ______________________________________ Cents From "0" Point of the Equal Scale Scale Tempered Chro- Step Major And/Or Pitch matic Scale Number Natural Minor Position ______________________________________ +18 7 Natural Minor +17 +16 3 Natural Minor + +15 +14 6 Natural Minor +13 +12 +11 +10 +9 +8 +7 +6 +5 +4 2 Major & Natural Minor +3 +2 5 Major & Natural Minor +1 "0" (Keynote) 1 Major & Natural --0 -1 -2 4 Major & Natural Minor -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 7 Major -13 -14 3 Major - -15 -16 6 Major ______________________________________
Although the ear will readily accept imperfect melodic intervals (2 notes sounding one after the other), even the most untrained ear will detect imperfections in harmonic intervals (2 notes sounding simultaneously). Thus, a workable system of integrating the scale of equal temperament and the scale of just intonation is necessary for acceptable intonation in the playing of harmonic intervals. A workable system requires basing the just scales on equal tempered starting points, or key notes. This results in each note having ten different pitches as it occupies different scale steps in various major and naturally minor scales in which it appears. As there are 12 different notes and each note will have 10 different pitches (as the note A has) a total of 120 different pitches are required for the notes of the 12 major and 12 minor scales of just intonation. Thus, a pitch adjuster which would provide for one position of adjustment at +16 cents, and another position of adjustment at -14 cents would enable a valved brass instrument manufactured to play in the equal temperament scale to play all 120 pitches in the just intonation scale. The differences of +4 cents to -2 cents can be easily and comfortably compensated for by the player with virtually no loss in tone quality.
There have been some attempts at providing valved brass instruments with some adjustment to enable the player to correct for these differences in intonation, but none have been successful for various reasons. One problem is that there are deficiencies in virtually every instrument manufactured which result in trumpets being unable to reproduce even the equal tempered scale. Furthermore, most of the prior art devices are mechanical gadgetry which permit the player to selectively extend or retract a valve slide crook for either the first or third valve. However, these corrections only aid those notes played with valve combinations incorporating their related valve and none other. Furthermore, there is no teaching of stopped positions provided to aid the player and instead he must rely upon his "ear" to adjust the tuning as he plays.
Other devices have suggested that the main tuning slide may be manually adjusted during play but again, unsightly contraptions are used with no suggestion as to the proper stopped positions required to adjust various notes of the scale according to the key being played. Furthermore, there is no recognition of the problems caused by the scale of equal temperament and no teaching of stopped positions to enable an instrument to play in the scales of just intonation. Some prior art correction devices greatly complicate the otherwise simple tuning of the instrument as they are coupled to the tuning slide crook. These correction devices are unsightly, heavy, and do not incorporate structure to automatically extend the third valve slide in combination with the tuning valve slide as is required to correct certain low notes played on the instrument.
To solve these problems, applicant has succeeded in developing an elegantly simple pitch adjuster which is fully calibrated and provided with manual stops which can be preselected to automatically correct notes of the equal temperament scale and bring them very closely into "tune" with the just intonation scale to thereby permit the playing of the just intonation scale in any given key.
Applicant's pitch adjuster provides for the coordinated movement of the third valve slide and tuning slide crooks and stopped positions are provided at +16 and -14 cents. A trigger control is positioned for operation by the left thumb and a rotatable finger ring is provided for operation by the second or third finger of the left hand so as to easily operate the pitch adjuster as the instrument is being played. The detent or stopped positions are provided by a tuning element fastened to the main push rod and a stop post assembly with an extendable center post which contacts upraised shoulders and prevents movement of the main push rod beyond the stopped positions. The tuning element has a center trough which enables the stop post assembly to screw down and prevent movement of the main push rod, thus disengaging the pitch adjuster and provide for playing of the instrument in the equal temperament scale. The tuning of the instrument may be easily accomplished through use of adjusting knobs which are threaded on the main push rod and which are mounted directly to the tuning slide crook so that the position of the tuning slide crook may be adjusted relative to the main push rod. This also centers the pitch adjuster about the newly tuned position of the horn and ensures that the newly tuned horn will play in the just intonation scale accurately and not be affected by the tuning adjustments required for the particular player. Applicant's pitch adjuster will also provide the proper adjustment to eliminate the sharpness or flatness of the horn when played through a mute. These and other advantages may be more fully understood by referring to the drawings and description of the preferred embodiment that follows.